Basic Problems
Disks are improving, but much less fast than CPUs
We can use multiple disks for improving performance
- By striping files across multiple disks (placing parts of each file on a different disk), we can use parallel I/O to improve access time
Striping reduces reliability -- 100 disks have 1/100th the MTBF (mean time between failures) of one disk
So, we need striping for performance, but we need something to help with reliability / availability
To improve reliability, we can add redundant data to the disks, in addition to striping